Part of what makes all the hatred for Common Core math so hilarious to me is that when I finally saw what they were teaching, it was a moment of "holy shit, this is exactly how I use and do math in real life." It's full of contextualizing with a focus on teaching mental shortcuts that allow you to quickly land on ballpark answers. I think it's absolutely wonderful.
But it's so foreign to the rote manner that a lot of parents were taught that many of them have a hard time grasping it, and get angry as a result.